1. Field of the Invention
The present invention relates to an apparatus and a method for automatically correcting deviation from a taught path due to deformation of a tool mounted on the wrist end of a robot during an operation by the robot.
2. Background of the Related Art
In general, a tool that is mounted on a wrist end of a robot for arc welding and sealing has an ellongated shape, and is more apt to be bent, even by a light impact, than tools for spot welding and handling. If programs for the robot are executed with the tool bent, naturally, the welding or sealing cannot be effected along a taught path.
Conventionally, if the tool is bent during operation, it is replaced in its entirety or corrected to a possible extent, and errors resulting from insufficient correction are adjusted by correcting a programmed path corresponding to the degree of error.
In order to carry out such repairing operation, however, the working line must be stopped for a long time, and the adjustment requires much time and labor, so that the manufacturing efficiency is lowered.
Moreover, the operation is performed along a wrong path without the attendance of an operator, so that defective products may possibly be manufactured.
The object of the present invention is to provide a tool shape correcting method and apparatus for a robot, in which the shape of a tool mounted on the wrist end of the robot is recognized before starting operation by the robot, whereby the deviation from a taught path attributable to deformation of the tool, if any, can be corrected automatically.
In order to achieve the above object, according to the present invention, a tool mounted on the wrist end of a robot and a camera for photographing the tool are first located in predetermined relative positions, images picked up by the camera are then returned and processed, shape data of the tool is obtained from the processed image data, the extent of deformation of the tool is detected by comparing the obtained tool shape data with reference tool shape data, and a taught path for the robot is corrected in accordance with the extent of the deformation.
According to the present invention, having the features described above, the extent of deformation of the the tool is detected before the operation by the robot is executed, and the taught path can be automatically corrected depending on the extent of the deformation, so that accurate operation can be performed even if there is some deformation of the tool.